Water flowing at a rate of 0.667 kg/s enters a countercurrent heat exchanger at 308 k and is heated by an oil stream entering at 383 k at a rate of 2.85 kg/s (c) = 1.89 kj/kg-k). the overall u = 300 w/m²-k and the area is 15.0 m². a. what is the heat transfer effectiveness? b. what is the heat transfer rate